Is this the year we see another Bay Bridge World Series? You don’t need to discuss it among yourselves. I’ll discuss it for you.

In 1989, Northern California citizens witnessed the first and only meeting between the A’s and Giants with baseball’s largest trophy at stake. Most of us remember the event because of the earthquake before Game Three.

I do, for certain. The tragedy and sadness and weirdness of that October isn’t something that leaves your brain. But neither does the memory of strange giddiness that preceded the earthquake, when our two Major League teams charged through the playoffs to reach the Series.

I recall riding in the car with our son, who turned 5 years old that month. He was an A’s fan. And he was excited about the “World Serious,” as he called it. But I was telling him how cool the whole thing was for the Bay Area, with both teams aboard.

“Dad,” he asked, “do the A’s and Giants play each other in the World Serious a lot?”

A child’s lack of perspective is a wonderful thing. For older fans on all sides of the bay, however, I mostly recall a lot of smiles as they looked at each other and uttered: “Man, how lucky are we?”

Very lucky, as it turned out. We haven’t come close to another Bay Bridge Series. Only three times since have both the Giants and A’s qualified for the playoffs in the same season. But this autumn, in many ways, has the same giddy feeling as 1989.

So is this finally the year we see the Giants and A’s again in the World Series?

Maybe the adrenaline of the last few weeks has overwhelmed me. But the way both teams won their division titles, navigating so many crazy twists and turns, makes me think we’ve got as good as shot as we’ll ever have at a Bay Bridge Redux.

Las Vegas does not agree. I checked the odds Thursday. The New York Yankees and Washington Nationals are favored to meet in the World Series. The A’s now have a slightly better chance (5-2) than the Giants (3-1) to get there, according to the bookmakers.

Balderdash, I say. Using my own systematic formula, I figure there is a 20 percent chance that we’ll have a 2012 Bay Bridge Baseballganza in three weeks.

My logic: This is the sixth time that the teams have reached the postseason simultaneously since 1968, when the A’s moved to Oakland from Kansas City. And out of the five previous occasions, they gave us one World Series. One in five. That’s 20 percent, right? Mathematics!

In case your memory is dim, let’s go over those other seasons to examine any similarities to this year:

1971 — The Giants won the N.L. West but lost to the hard-hitting Pirates in the league championship series. The A’s won the American League West but lost to the experienced Baltimore Orioles in the first round — although the defeat was a precursor to three consecutive World Series for Oakland. This time around, both are again division champions and facing similar foes. The Giants are up against the Reds’ big bats and Oakland is meeting the more playoff-tested Tigers. Might not be a good omen.

1989 — See above. Unless you’re younger than 26 or 27, you haven’t forgotten. The A’s and Giants, after winning their divisions, each took just five games to blitz through their respective League Championship Series. And then, bracketed around the earthquake misery, the A’s proved they were baseball’s best team with a sweep of the Giants.

2000 — The Giants finished with the best regular season record in all of baseball but shockingly lost to the wild card New York Mets in the division series. The A’s won the West but were defeated by the favored Yankees in the ALDS. Talk of a Bay Bridge Series never really percolated. Instead, we were treated to an obnoxiously hyped-up matchup between the Yankees and Mets. The Yankees won the Series in five games.

2002 — The Giants finished second in the N.L. West to Arizona but as a wild card plowed through the playoffs before losing to the Angels in the World Series. The A’s won 103 games to take the A.L. West but lost to Minnesota in the ALCS. The Angels were the A.L. wild-card entry and advanced to the World Series to meet the Giants, who won three of the first five games and were ahead in Game Six when … well, never mind.

2003 — The Giants again won the West, going wire to wire, but were dumped unceremoniously by the Florida Marlins in four games. (Jose Cruz Jr.’s dropped fly ball in Game Three extra innings still haunts.) The A’s were also division winners and won the first two games of the ALDS against Boston but then lost three straight games to the Red Sox and went home.

For any team, as you can see, there are many more ways the playoffs can go bad than good. It also holds true this time. There’s a reason 1989 was so rare. Here’s how long ago that was: Our kindergarten-aged son is now pursuing a doctoral degree in science at UC Irvine. He can surely calculate the true and actual odds of another Bay Bridge Series.

I distinctly remember, however, what I told him that day when he asked how often the A’s and Giants played for the world title.

“No,” I told him, “it doesn’t happen a lot. It hasn’t happened ever before. It might not ever happen again. So we’d all better sit back and enjoy it.”

It would be fun if, a few weeks from now, other parents could have the same sort of conversation with their kindergartners. I’m sticking with my prediction of a 20 percent chance. After what we’ve seen from the Giants and A’s over the last few weeks, anyone want to argue?